Preparation Of Highly Loaded Benzoquinone Porous Carbon Cathode And Its Electrochemical Performance In Zinc-Based Aqueous Batteries

With China’s“Peak carbon dioxide emissions and Carbon neutrality”target proposed,renewable energy will gradually move from alternative energy to the main energy,new energy secondary batteries as a kind of electrochemical energy storage technology because of its relative safety,high efficiency,low cost,flexible application and other characteristics,is considered to be the realization of clean renewable energy wide coverage and carbon neutral.The key link is to achieve wide coverage of clean renewable energy and carbon neutrality.Therefore,it is very important to develop a new energy storage technology with high safety,high stability and environmental friendliness.Among many emerging secondary battery systems,zinc-benzoquinone battery has become a very competitive new energy storage system with its advantages of high energy density,low cost and abundant raw material reserve.The key point to realize the high performance zinc-benzoquinone aqueous battery is to construct porous carbon cathode material with high efficiency loading of benzoquinone.In this work,glucose as the carbon source,melamine as the nitrogen source and potassium oxalate monohydrate as the pore-forming agent were selected to regulate the pore structure of porous carbon materials by changing the carbonization temperature during high temperature synthesis.It was found that the nitrogen-doped porous carbon materials prepared at a carbonization temperature of 900℃had a high specific surface area(2202.756 m² g^-1)and pore volume(1.174 cm³ g^-1),and the corresponding zinc-benzoquinone aqueous cells exhibited excellent electrochemical performance.This is mainly due to:on the one hand,its abundant micropores（1.0～2.0nm）can effectively anchor the benzoquinone,resulting in a high benzoquinone loading of 44.0%.On the other hand,the micro mesoporous structure（2.0～4.0 nm）can also adsorb electrolyte to wet the electrode and improve the electrochemical performance of the cell.The capacity can reach 493.0 m Ah g^-1 at 1.0 C under low-magnification cycle,which is close to the theoretical specific capacity of benzoquinone(496.0 m Ah g^-1),while the specific capacity of 162.1 m Ah g^-1 is maintained after 600 cycles at 5.0 C under high-magnification charge/discharge environment,with a capacity retention rate of 61.6%,showing a superior performance.In order to accelerate the redox reaction rate of aqueous Zn-benzoquinone battery,improve its high-magnification performance and cycling stability,so as to realize the excellent charge/discharge stability and long cycle life of aqueous Zn-benzoquinone battery at high magnification,iodine,a halogen element,was selected as the catalyst.It is shown that the addition of halogenated iodine reduces the activation energy of the redox reaction of the organic cathode material benzoquinone and promotes the electrochemical reaction rate of the aqueous Zn-benzoquinone battery,and the aqueous Zn-benzoquinone battery with iodine as an additive exhibits a high discharge capacity of 498.1 m Ah g^-1 and a small degree of polarization at a multiplicity of 0.5 C.The iodine-catalyzed effect becomes more and more significant as the multiplicity increases,and the capacity is still maintained at 64.5%when transitioning from 0.1 C to 5.0 C multiplicity,and the specific capacity is almost 100%restored to its respective level when returning from large to small multiplicity,showing excellent cell multiplicity performance.After 18,000 charge/discharge cycles at a multiplier of 10.0 C,the battery still has a discharge specific capacity of 178.3 m Ah g^-1 and an average Coulomb efficiency of 99.5%.Based on the excellent cycling performance and multiplication performance,it is important to further promote the practical application of zinc-based aqueous secondary batteries.